It is an object of the invention to provide the novel compounds of formula I and a process and intermediates for their preparation.
It is another object of the invention to provide the novel compounds of formula III and a process for their preparation.
These and other objects and advantages of the invention will become obvious from the following detailed description.
The novel compounds of the invention are compounds of the formula
wherein R is selected from the group consisting of hydrogen, alkyl of 1 to 18 carbon atoms and aryl and aralkyl of up to 18 carbon atoms and the amine is optionally protected.
Examples of R as alkyl are methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl and tert-butyl and as aryl or aralkyl are benzyl and naphthyl.
Preferred compounds of the invention have the formula 
wherein A is defined as above, R2 is hydrogen and R1 is selected from the group consisting of 
Ra, Rb, Rc and Rd are individually selected from the group consisting of alkyl of 1 to 18 carbon atoms, aryl and aryl of up to 18 carbon atoms and mono- or polycyclic containing at least one heteroatom and X is selected from the group consisting of hydrogen, alkyl of 1 to 8 carbon atoms and aryl of up to 14 carbon atoms or R1 and R2 together with the nitrogen to which they are attached form a mono- or polycyclic with at least one heteroatom.
Examples of cyclic protective groups are 
A preferred compound of formula I has the formula 
wherein R is alkyl of 1 to 8 carbon atoms, especially 1,1-dimethylethyl.
The process of the invention for the preparation of a compound of formula I comprises reacting a compound of the formula 
in racemic form at the 6-member ring and R is as defined and above the amine is protected with a dehydrogenation agent to form the corresponding compound of formula I.
Preferably, the starting material has the formula 
wherein R, R1 and R2 have the above definitions and the dehydrogenation agent is a strong base, an oxidizing agent or a sulfur or selenium derivative.
The compounds of formula II are racemic (SR+SS) at the level of the 6-member ring and are novel products. They can be prepared by the following process. 
The starting compounds of the said process are described in or can be prepared as set forth in J. Chem. Soc. Perkins Trans. 1 (1979), Vol. 6, p. 1451-1454 Chem. Soc. Chem. Comm. (1977), p. 635-36.
The process of the invention for the preparation of a compound of the formula
wherein R is defined as above and the amine is optionally protected comprises reacting a compound of formula I with a reducing agent.
Preferably, the resulting compound has the formula 
wherein R, R1 and R2 are defined as above and the reducing agent is hydrogen in the presence of Raney nickel, palladium on carbon, palladium dihydroxide in the presence of talc, ruthenium on carbon or rhodium in the presence of aluminum, more preferably hydrogen in the presence of Raney nickel. The reaction is effected in the presence of a solvent such as acetic acid, methanol, ethanol, isopropanol, dimethoxyethane, butanone, DMF or acetonitrile.
The compounds of formula IIIA are intermediates for the preparation of pharmacological products such as the compounds described in EP Patent No. 84,095 and in J. Chem. Soc. Perkin Trans. 1, (1986), p. 1011. Other products of formula II are useful in a similar process.
The products of formula II and IIA in the SR form or the form of a mixture (SR+SS) are novel intermediates as are the compounds of formula III and IIIA with the proviso that R is not hydrogen or tert.-butyl in formula III and in formula IIIA, R is not hydrogen or tert.-butyl when the amine is protected by phthalimido. EP 94,095 describes a compound of formula IIIA when R is tert.-butyl and the amine is phthalimido.